Device for repointing twist drills



Dec. 7, 1948. D. CROWTHER 2,455,562

DEVICE FOR REPOIN'IING TWIST DBILLS Filed Nov. 12, 1946 INVENTOR I BY ATTORNEY My: invention relates to devices "for re-pointing f twistdrills. It relates moreparticularly to a device by means of which a drill to be re-pointed is supported in proper angular relation to a grindw 5w, Figul'l) is a' viewin 'section ontheline l -t of 0f the inventionis toprovide a devicebfthi r-- -1 l 5 acter which is simple and inexpensive to rnanu venint for supporting a arm 50 that it may have t its cuttingend' properlybrou ht into engagement m: Referrirl fiot construction shown intheacl companying drawings inorder to illustrate "the In the drilling arti a twist drill has a body poi tion provided wltha pointflthe latter termbeing used to designate the entirecutting end: Two

deeply jcut helical grooves 1 known as flutes extendtion of cutting 1ips-produced by the flutes]; "This tip must be kept during "-the sharpening operation heel is theportioniofthe pointback or the cutting lips; *efficient cutting; edge "for the lips 1 would t not be providedunless they are sharp. So in order to produce this cutting edge, the surface of the point must be ground exactly back i of the 1 I-llpjs; i this being known as lip clearance. This clearance allows thelipsto enter the metal or material which is being drilled, and the 'effectiveness of the drill depends largely on the grinding of l the lip clear I with relation to the axis. With the foregoing ex- *planationinsmind, it willwbaunderstood that la 1&3 special object "ofimy invention is to provide ,a. devicebymeans oiiwhlchtthe anglescjust referred to may be conveniently and iaccuratelyflgroundw in order to provide thefdrill with the proper point.

tic of this invention are setforth withparticularity in the appended claims. Theinvention, however bothnasxto its organization andmethod of advantages thereof,will be best understood from the following description of specific embodiments thereof when read in connection withthe acco showing the point oiba drill in proximity toa grinding wheel.

Fig. 2 is a top plan view looking in the direction indicated by the arrow 2 in Fig. 1.

ATENT OFFER 1 DEVICE r0111mronv'rnm rvvls'r nmnns David new man November 12, 1946; semi swam 3 Claims (ll.51r2l9bw rrrn ismrlzs;

showing= some ot the mire-em forms of openings which may be made therein, these views being in} l the direction of the arrow ain Fig. 1

Fig. 11 is amelevationalview oif anothertorin of bracket support. if Fig. 12 is a plan view of this iorm of bracket.

rinci les a d signate upper en 9 volved in this invention, the numeral horizohta l surface such as the berich B of a grind ing ma'chin A pairbfclamping plates 1 2 are pro vided with 'longitudinalwshaped grooves 13in their surfaces which face each other, 'the two 2o glOOVGS-f" being parallel to "each 11 othert These in the exact center of the axis ofthedrilli The plates i are made of: any suitable material suclr as steeli *Wl ien they 1 are square in shape as shown; they 1 are so positioriedin i operation that corners or points thereof arc-located nearest to the-face of a gri'nding wheel G." I-Iowever the shape of these plates is not a material feature so long as reduced part thereof is directed toward the grind ing Wheel in order that no part of the plates shallcome to engagement w wheel uring the whi I vesgl igr z,

A bolt or l threaded stud is r secured at one 1 of its ends to each of theplates I 2, the projecting end 1 being threa'de'd to receive a knurled nut l 5.

bracket support having an inclined d a horizontallowerend ill: The lsuendportion I 0 is secured by screwbolts l l to a-- diametrically opposite each other along member portionof thedrill.Asharp tip at the extreme forward end of the drill is formed by the intersc l the upper -end portion on abracket support 30 I bac and forth indvernent oi the clamping plates ioldihg a drill Djto bei pointed in the v- 1 hls'inovement is indicated int of the bolts 14" passes through a hole 5 I 6 in 1 the 11 opposed plate before the nuts I5 are applied, 40 There The novel feature's which I believe characterislel matinegrteves 1 3 are exactly midway between thei two bolts l Fig. 3, 4, 5, 6, 7, 8 and 9 are fragmentary views 56 ground exactly like the lip previously ground.

' s lt with reduced r cylindrical porl adapted td be clanipedfiupon thr t gp faces oi;;-the "twoplates respectively. It will now be understood hat when the two plates are as operation, together with additionalFobjects and serribled the bolts extend inoposite directions ndspaced: from each other-in a i I I vertical dircti n. "'lri-otherwordsl the two paral p andiat right angles to a line Figfil isa side elevational viewof the"devic so extending betiveen l tlie bbltsfi I Therefore "when ings 20 which do not extend through either edge of the support 9. In operation, the cylindrical portion 18 associated wtih the downwardly extending bolt M will be placed in a slot l9 or an formed for one half of the cutting end, the clamping device is removed from the bracket, turned over and the other bolt [4 applied to the bracket, so that the other half of the drill is ground exactly like the first half. The use of this device insures this desirable result since it is not nece sary to loosen the drill in the clamping device for the two grinding operations. When the bracket support is provided with two openings, the lower operator, the provision of the cylindrical portion, drills. l8 permits the holder assembly to be given a? -"""Iclaim:

limited back and forth mOVEMBYifipWiQZF-EIglgtmlifk L'QIHR E'dE'YiQBFfOIQl'E-IJOiHtil'lg twist drills, the to the face of the grinding wheel in orderto grind gombination of a drill clamping holder embodythe proper clearance back of the lifi ofithti -"drfif l ing two clainpiiig plates having opposed longiwhich at the same time is being ground atstheg tudinal grooves inotheir surfaces for receiving proper angle. a dr'ill'be'tweenthem', said plates containing holes As shown in Fig. 1, I provide an upwardly iexse e uangeispaced laterally from said grooves, a tending threaded stud Zliiprovided with a nut clamping bolt secured to each of said plates and 2 2 vadapted qtplhe turnefixmweiorylesssiowmomthe :2 extending in opppsitei directionsethrouamthahm' stud-sothat theextentof'hoieainlthevnutiaboveith tomonthe;stud-c nsummatesawersvhiemmmbe:

used to forrextendinefiabeynndi the;2-:1101dems.;ThiSl length V may be decreased or increased according J10 1J1; said holden with i 6331;195:4150ythmfacggqfmimam ing wheeln-s Y t v of ,the associa-tedimlate ann :a; support tforllsaidm old c n-t n ianu eninem-in twhichseith' mu: i a b tsmawbep aced toserreiesiwnivgtrra 4 in in ze -ia t oxth-ilatsmi moreme iimf m .4 d iqs dp reintieetwi w iliathoia mb i et qe 19 d illircl m sih ldea mbo ie not ifi'n an elbh x-depfihl lthe 6x905 ediholfe whenthe' ;.ing 'twot; clampinga plates having ppggd ,lqn i a ime d nthrhaslbe n zd zt rmin de i iz sszll and 'l ehowsadifier n iiormioi bruckete s nnartifrorithedrillz --iTh1s.-.bracket iconsistszn 3 U shap d; dien rt mlumthe-two endsmfawmome:e en edtansma mu warditozeonstitutath mbers zifinid'iz xof aidruhh ldenysun rtui' hl curvfid pqrtion- -of t-hei-u men bemis prpvided wzithi a 9E21] t roug wl clu "s curinsiboltaaanas si;r. poni e instthiszb ltethe drill ihoiderisupp r can; be-"ztilted at, any; desired anglev andtthemse curediimsuc ositio -th turninetthe holtrd wn tudinal grooves in their surfacegetor receiyingm ln d p a ic n e einsr h ass uaflwme t rellvri' e wwm K Q YQSce emnmemoltesew cuned eto i -eaeh oftsaid plates andz extending in opposite;diroptions; throughvtheshole;.of (the insu n soeiatedyplatema i a b a k tmavmelamincli edaa ereo Mid lfis m mb s edtt 's nvw:

as a pivoador swingingtbaclc and i'fotth- Jami 8' mov m nto s idh ld aw r yr t o theme ofiargrinding illl ieeL-i-s I i The; downwardlyi-extending lgnurledlnuthi5 enters-11 3. In, a device ftor re pointing twistiairills thaw 'r DB-G i izit'heeu membem-lTmsy-vspaee ior ers mbin ion i d i lw a nn naiholde rembn w a aonenne whiehl memo eaof ifl flfb l fi ihfiwgeet oic a m ate h v ngw mse slqnm ineenutsl-lfi may be -pla d t rsenvei asa pivotfo ist din h feo e ri vt emis iflcessi sr eiv n swinging-hack and: forth glatenal movementivof-itheg 1= drill isaidaplates containing, holes equa llytspacod-r whqlderi pror-id dab athi naizto z mnmet ra y t o a ids oevese a, c a p n -ma a s 2.8 0 1 i curedetote h-oi!s dsp ate w mie teudm amuv i. pezzatiomfa d.kadvantae azw wmy -inv n-wopuos-ite d re t set ronehath h l eofrit erasa ms-will be rread yi understo d in.i nneetiomisoesociated plate-,isa ,iJ- sh'aipedl bracket i havingogmu-a with" the fore oin i-ries ripti mia dy eirza c m z gmarlyextemdingaerrdinortionaionsnmortingisaidm: panyin td awinssaiInse tion-etc?r p intna drill}; holderesithechspalce lbetween t-the -rarmszaof es'aidnUQi? when it becomes dull, it is placed between them membemforminggganigpgningin, which;eithemoneari; two.r'groovesmhicmIue e ch oth rimme plat s; of 'sfaid':rboltagmaiyl beiplacedntoIsenveazas-za.piyotqse'i l2 ndwjwith the E EHQ' MM P ojectin 255 ior :swinging-nbacklsanmdorthi;:lateral? movement a t ezp oper idistancems.sho nnfirmi- Imo d of saidtnoldemwith erelatiox'izto theifabelof a rimh cunatelyadetermi e it lisiidistancemae sier ing-swheelglflieiouri-ved'portionmf sairizbracke'bdom such s.:.ishowmin zthisiifi m fi mz -I--Z j*- b tainingn'a slot;?,anct3 a seourin'gibolti passing rides: h k 1d ts 5 at d d to justabiyi-mthroughzrsaidlslotxt i n w ..e=.;nure, nu 1: 81126: 1 enaume. 1 O n? 60m M s ,7, clamn the idrillyindflwe ,One'.;of the bolts EMF-{IS e. mwnsceqwtrrmathemap iied tothezupnerap rt on ofith ib a eto l i l i i withitheicylindricahportion1-l;8;inithe.:opeuing or? V s zap wided gatherein cfl lw i 8 93 1 '1 3 51 a The izfollowingnreterenceseare of recordxin (theatre fifi meeorthisii atent-ai i W i r N T WS E W T r"? a pivotwthisymoilemimt,servingetpigrind th Numbensa Namea v. crane drill to-f providei't mpmp l tflnfilfl'Q g p 1,576,311 mgsawman .1

' at mana in Yanflss 5 43.1 

